Dinosaur Discovery Makes Hearts Skip a Beat

In the increasingly Disney-fied world of paleontology, it doesn't take a whole lot to get people excited. And Thursday, a piece of news emerged that thrilled even the most unscientific corners of society. Effectively negating years of pessimism over the chances of ever finding one, researchers at the North Carolina Museum of Natural Sciences in Raleigh have uncovered the softball-size remains of a heart inside the fossilized skeleton of one of their dinosaurs. And what a find it is: The Thescelosaurus pumper, which may be the first dinosaur heart ever seen by human eyes, is decidedly un-reptilian; it's divided into four chambers and fed by a single aorta. This structure, scientists explain, suggests that the dinosaur in question was warm-blooded, like birds and mammals, rather than cold-blooded, like snakes and lizards.

This is a major development, says TIME senior writer Frederic Golden, particularly in light of the public's fascination with all things dinosaur. "Anything that advances our understanding of these marvelous creatures is bound to be met with a great deal of excitement," he says. And it doesn't hurt that this particular find feeds into one of the most vigorous debates surrounding our prehistoric friends: The all-important distinction between warm blood and cold blood. There has been a longstanding controversy over dinosaurs' place in the evolutionary family tree; some scientists maintain the giant lizards were the ancestors of modern birds, while others believe they predated today's cold-blooded reptiles. This heart, explains Golden, could lend indisputable weight to the theory that most or all dinosaurs had warm blood coursing through their veins, because it was found in an animal known to be a vegetarian  which were once thought to be exclusively cold-blooded.